The kinetics of the oxidation of Si in a microwave excited O2plasma have been studied at temperatures in the range of 260–390 °C. The substrate was positively biased and the total electron and O−ion current maintained constant by application of an electric field ∼5 MV cm−1across the growing oxide. This field was established for thicknesses ≥10 nm. Total current densities were 2–6 mA cm−2while the O−current was estimated to be 0.02–0.04 mA cm−2. Oxide growth kinetics are discussed in terms of a recent physical model. Chemical etch rates and refractive indices were measured and although similar to those of thermal oxide, infrared absorption spectra suggest that the internal network structure is not the same. ©1995 American Institute of Physics.